A novel biosensor based on activation effect of thiamine on the activity of pyruvate oxidase

A designed self-microemulsion delivery system for dihydromyricetin and its dietary intervention effect on high-fat-diet fed mice

The present study aims to design a self-microemulsion delivery system (d-α-tocopheryl polyethylene glycol 1000 succinate - quillaja saponin) to enhance the absorptivity of dihydromyricetin (DMY-S), and to investigate its dietary intervention effect on high-fat-diet (HFD) fed mice. We find DMY-S can inhibit the increase of body weight and fat mass, preventing non-alcoholic fatty liver disease. Compared to the model group, the abundance of mice intestinal flora is mainly changed in certain bacterial genera of Firmicutes and Bacteroides, including norank_f_Muribaculaceae and Blautia. The result of metabolism analysis indicated that the expression levels of cincassiol B, creatine, pantothenic acid and aminobutyric acid in the liver tissues of mice treated with DMY-S showed a down-regulation. The DMY-S prevented hyperlipidemia in HFD mice mainly by affecting different pathways including glycerophospholipid metabolism, sphingolipid metabolism and pantothenate and CoA biosynthesis.

An improved enzyme nanoparticles based amperometric pyruvate biosensor for detection of pyruvate in serum

The nanoparticles of commercially available pyruvate oxidase (POx) from Aerococcus species were prepared by desolvation method, which were then characterized and covalently immobilized onto gold electrode (AuE) to construct an improved model of amperometric pyruvate biosensor. The POxNPs/Au electrode was analyzed morphologically by scanning electron microscopy (SEM). On the other hand, cyclic voltammetry studies (CV) and electrochemical impedance spectroscopy (EIS) helped in deciphering the electrochemical properties of the electrode at different stages of construction. The biosensor showed optimum response within 7.5 s, at a potential of 0.28 V, pH 5.5 and 35 °C. A linear relationship was observed between biosensor response i.e. current (μA) and pyruvate concentration in the range, 0.01 μM - 5000 μM, with a lower detection limit of 0.67 μM. The analytical recovery of added pyruvate in sera was 99.0% and 99.5% within and between batch coefficient of variation (CV) were 0.045% and 0.040% respectively. The working electrode displayed an excellent correlation coefficient (R² = 0.99%) between levels of pyruvate in sera, as detected by the standard spectrophotometric method and the present biosensor. The biosensor was utilized for detection of total pyruvate level in sera of apparently healthy individuals and patients suffering from cardiogenic stress, more specifically cardiac failure. The activity of the biosensor deteriorated by 25%, after its regular use over a period of 240 days, while being stored dry at 4°C.

Thiamine Assays-Advances, Challenges, and Caveats

Thiamine (vitamin B1) is essential to the health of all living organisms and deficiency has long been associated with diseases in animals such as fish, birds, alligators, and domesticated ruminant mammals. Thiamine is also implicated in several human diseases including Alzheimer's, diabetes, dementia, depression and, most notably, Wernicke-Korsakoff syndrome and Beriberi disease. Yet, highly sensitive and specific detection of thiamine remains an analytical challenge, as pM to nm levels of thiamine need to be detected in environmental and human samples, respectively, various phosphorylated variants need to be discriminated, and rapid on-site detection would be highly desirable. Furthermore, appropriate sample preparation is mandatory, owing to the complexity of the relevant sample matrices including fish tissues, ocean water, and body fluids. This Review has two objectives. First, it provides a thorough overview of analytical techniques published for thiamine detection over the last 15 years. Second, it describes the principles of analytical approaches that are based on biorecognition and may open up new avenues for rapid and high-throughput thiamine analysis. Most notably, periplasmic binding proteins, ribozymes, and aptamers are of particular interest, as they function as bioaffinity recognition elements that can fill an important assay technology gap, owing to the unavailability of thiamine-specific commercial antibodies. Finally, the authors provide brief evaluations of key outcomes of the major assay concepts and suggest how innovative techniques could help develop sensitive and specific thiamine analytical test systems.

Hydrophobin-Based Surface Engineering for Sensitive and Robust Quantification of Yeast Pheromones

Detection and quantification of small peptides, such as yeast pheromones, are often challenging. We developed a highly sensitive and robust affinity-assay for the quantification of the α-factor pheromone of Saccharomyces cerevisiae based on recombinant hydrophobins. These small, amphipathic proteins self-assemble into highly stable monolayers at hydrophilic-hydrophobic interfaces. Upon functionalization of solid supports with a combination of hydrophobins either lacking or exposing the α-factor, pheromone-specific antibodies were bound to the surface. Increasing concentrations of the pheromone competitively detached the antibodies, thus allowing for quantification of the pheromone. By adjusting the percentage of pheromone-exposing hydrophobins, the sensitivity of the assay could be precisely predefined. The assay proved to be highly robust against changes in sample matrix composition. Due to the high stability of hydrophobin layers, the functionalized surfaces could be repeatedly used without affecting the sensitivity. Furthermore, by using an inverse setup, the sensitivity was increased by three orders of magnitude, yielding a novel kind of biosensor for the yeast pheromone with the lowest limit of detection reported so far. This assay was applied to study the pheromone secretion of diverse yeast strains including a whole-cell biosensor strain of Schizosaccharomyces pombe modulating α-factor secretion in response to an environmental signal.

Electrochemical sensor based on a bilayer of PPY–MWCNTs–BiCoPc composite and molecularly imprinted PoAP for sensitive recognition and determination of metolcarb

A molecularly imprinted electrochemical sensor for metolcarb detection was constructed by electropolymerizing a poly-o-aminophenol membrane after the modification of a composite that consisted of polypyrrole MWNTs and binuclear phthalocyanine cobalt(ii) sulfonate on a GCE surface.

Catalase mimic property of Co3O4 nanomaterials with different morphology and its application as a calcium sensor

The applications of inorganic nanomaterials as biomimetic catalysts are receiving much attention because of their high stability and low cost. In this work, Co3O4 nanomaterials including nanoplates, nanorods, and nanocubes were synthesized. The morphologies and compositions of the products were characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The catalytic properties of Co3O4 nanomaterials as catalase mimics were studied. The Co3O4 materials with different morphology exhibited different catalytic activities in the order of nanoplates > nanorods > nanocubes. The difference of the catalytic activities originated from their different abilities of electron transfer. Their catalytic activities increased significantly in the presence of calcium ion. On the basis of the stimulation by calcium ion, a biosensor was constructed by Co3O4 nanoplates for the determination of calcium ion. The biosensor had a linear relation to calcium concentrations and good measurement correlation between 0.1 and 1 mM with a detection limit of 4 μM (S/N = 3). It showed high selectivity against other metal ions and good reproducibility. The proposed method was successfully applied for the determination of calcium in a milk sample.